There is a gradual decrease in impact strength with increase in filler content for both RHP and talc composites (Fig. 8). When a crack is generated [25] due to an impact it propagates towards a poor interfacial region. Therefore, as the filler content increases, impact strength tends to reduce gradually. On the other hand, if the filler matrix adhesion is very strong, fillers restrict the mobility of the matrix molecules. In turn, this also results in reduction in impact strength. It is well known that the stiffest composites exhibit the lowest impact properties as the high stress is transferred from the polymer matrix to the filler particles.